Biblio

In this paper, a new model-free adaptive sliding mode load frequency control (LFC) scheme is designed for inter-connected power systems, where modeling is difficult and suffers from load change disturbances and denial of service (DoS) attacks. The proposed algorithm only uses real-time I/O data of the power system to achieve a high control performance. Firstly, the dynamic linearization strategy is used to build a data-based model of the power system, and intermittent DoS attacks are modeled by limiting their duration and frequency. Secondly, the model-free adaptive sliding mode control (MFASMC) scheme is designed based on optimization theory and sliding mode reaching law, and its stability is analyzed. Finally, the three-area interconnected power system was selected to test the presented MFASMC scheme. Simulation data shows the effectiveness of the LFC algorithm in this paper.

In this paper, a sliding mode control (SMC) based on nonlinear disturbance observer and intermittent control is proposed to maximize the security of cyber-physical systems (CPSs), aiming at the cyber-attacks and physical uncertainties of cyber-physical systems. In the CPSs, the transmission of information data and control signals to the remote end through the network may lead to cyber attacks, and there will be uncertainties in the physical system. Therefore, this paper establishes a CPSs model that includes network attacks and physical uncertainties. Secondly, according to the analysis of the mathematical model, an adaptive SMC based on disturbance observer and intermittent control is designed to keep the CPSs stable in the presence of network attacks and physical uncertainties. In this strategy, the adaptive strategy suppresses the controller The chattering of the output. Intermittent control breaks the limitations of traditional continuous control to ensure efficient use of resources. Finally, to prove the control performance of the controller, numerical simulation results are given.

We investigate the fuzzy adaptive compensation control problem for nonlinear cyber-physical system with false data injection attack over digital communication links. The fuzzy logic system is first introduced to approximate uncertain nonlinear functions. And the time-varying sliding mode surface is designed. Secondly, for the actual require-ment of data transmission, three uniform quantizers are designed to quantify system state and sliding mode surface and control input signal, respectively. Then, the adaptive fuzzy laws are designed, which can effectively compensate for FDI attack and the quantization errors. Furthermore, the system stability and the reachability of sliding surface are strictly guaranteed by using adaptive fuzzy laws. Finally, we use an example to verify the effectiveness of the method.

The compressed sensing (CS) method can reconstruct images with a small amount of under-sampling data, which is an effective method for fast magnetic resonance imaging (MRI). As the traditional optimization-based models for MRI suffered from non-adaptive sampling and shallow” representation ability, they were unable to characterize the rich patterns in MRI data. In this paper, we propose a CS MRI method based on iterative shrinkage threshold algorithm (ISTA) and adaptive sparse sampling, called DSLS-ISTA-Net. Corresponding to the sampling and reconstruction of the CS method, the network framework includes two folders: the sampling sub-network and the improved ISTA reconstruction sub-network which are coordinated with each other through end-to-end training in an unsupervised way. The sampling sub-network and ISTA reconstruction sub-network are responsible for the implementation of adaptive sparse sampling and deep sparse representation respectively. In the testing phase, we investigate different modules and parameters in the network structure, and perform extensive experiments on MR images at different sampling rates to obtain the optimal network. Due to the combination of the advantages of the model-based method and the deep learning-based method in this method, and taking both adaptive sampling and deep sparse representation into account, the proposed networks significantly improve the reconstruction performance compared to the art-of-state CS-MRI approaches.

In response to the vulnerabilities in traditional perimeter-based network security, the zero trust framework is a promising approach to secure modern network systems and address the challenges. The core of zero trust security is agent-centric trust evaluation and trust-based security decisions. The challenges, however, arise from the limited observations of the agent's footprint and asymmetric information in the decision-making. An effective trust policy needs to tradeoff between the security and usability of the network. The explainability of the policy facilitates the human understanding of the policy, the trust of the result, as well as the adoption of the technology. To this end, we formulate a zero-trust defense model using Partially Observable Markov Decision Processes (POMDP), which captures the uncertainties in the observations of the defender. The framework leads to an explainable trust-threshold policy that determines the defense policy based on the trust scores. This policy is shown to achieve optimal performance under mild conditions. The trust threshold enables an efficient algorithm to compute the defense policy while providing online learning capabilities. We use an enterprise network as a case study to corroborate the results. We discuss key factors on the trust threshold and illustrate how the trust threshold policy can adapt to different environments.

Cyber attacks keep states, companies and individuals at bay, draining precious resources including time, money, and reputation. Attackers thereby seem to have a first mover advantage leading to a dynamic defender attacker game. Automated approaches taking advantage of Cyber Threat Intelligence on past attacks bear the potential to empower security professionals and hence increase cyber security. Consistently, there has been a lot of research on automated approaches in cyber risk management including works on predictive attack algorithms and threat hunting. Combining data on countermeasures from “MITRE Detection, Denial, and Disruption Framework Empowering Network Defense” and adversarial data from “MITRE Adversarial Tactics, Techniques and Common Knowledge” this work aims at developing methods that enable highly precise and efficient automatic incident response. We introduce Attack Incident Responder, a methodology working with simple heuristics to find the most efficient sets of counter-measures for hypothesized attacks. By doing so, the work contributes to narrowing the attackers first mover advantage. Experimental results are promising high average precisions in predicting effiective defenses when using the methodology. In addition, we compare the proposed defense measures against a static set of defensive techniques offering robust security against observed attacks. Furthermore, we combine the approach of automated incidence response to an approach for threat hunting enabling full automation of security operation centers. By this means, we define a threshold in the precision of attack hypothesis generation that must be met for predictive defense algorithms to outperform the baseline. The calculated threshold can be used to evaluate attack hypothesis generation algorithms. The presented methodology for automated incident response may be a valuable support for information security professionals. Last, the work elaborates on the combination of static base defense with adaptive incidence response for generating a bio-inspired artificial immune system for computerized networks.

Intrusion detection is a traditional practice of security experts, however, there are several issues which still need to be tackled. Therefore, in this paper, after highlighting these issues, we present an architecture for a hybrid Intrusion Detection System (IDS) for an adaptive and incremental detection of both known and unknown attacks. The IDS is composed of supervised and unsupervised modules, namely, a Deep Neural Network (DNN) and the K-Nearest Neighbors (KNN) algorithm, respectively. The proposed system is near-autonomous since the intervention of the expert is minimized through the active learning (AL) approach. A query strategy for the labeling process is presented, it aims at teaching the supervised module to detect unknown attacks and improve the detection of the already-known attacks. This teaching is achieved through sliding windows (SW) in an incremental fashion where the DNN is retrained when the data is available over time, thus rendering the IDS adaptive to cope with the evolutionary aspect of the network traffic. A set of experiments was conducted on the CICIDS2017 dataset in order to evaluate the performance of the IDS, promising results were obtained.

In this paper, the adaptive event-triggered asymptotic tracking control with guaranteed performance for a single link robot manipulator (SLRM) system driven by the brush DC motor is studied. Fuzzy logic systems (FLS) is used to approximate unknown nonlinear functions. By introducing a finite time performance function (FTPF), the tracking error of the system can converge to the compact set of the origin in finite time. In addition, by introducing the smooth function and some positive integral functions, combined with the boundary estimation method and adaptive backstepping technique, the asymptotic tracking control of the system is realized. Meanwhile, event-triggered mechanism is introduced to reduce the network resources of the system. Finally, a practical example is given to prove the effectiveness of the theoretical research.

The main aim of the Internet of things is to improve the safety of the device through inter-Device communication (IDC). Various applications are emerging in Internet of things. Various aspects of Internet of things differ from Internet of things, especially the nodes have more velocity which causes the topology to change rapidly. The requirement of researches in the concept of Internet of things increases rapidly because Internet of things face many challenges on the security, protocols and technology. Despite the fact that the problem of organizing the interaction of IIoT devices has already attracted a lot of attention from many researchers, current research on routing in IIoT cannot effectively solve the problem of data exchange in a self-adaptive and self-organized way, because the number of connected devices is quite large. In this article, an adaptive neuro-fuzzy clustering algorithm is presented for the uniform distribution of load between interacting nodes. We synthesized fuzzy logic and neural network to balance the choice of the optimal number of cluster heads and uniform load distribution between sensors. Comparison is made with other load balancing methods in such wireless sensor networks.

The study of networks is an extensively investigated field of research, with networks and network structure often encoding relationships describing certain systems or processes. Critical infrastructure is understood as being a structure whose failure or damage has considerable impact on safety, security and wellbeing of society, with power systems considered a classic example. The work presented in this paper builds on the long-lasting foundations of network and complex network theory, proposing an extension in form of rebalance based flow centrality for structural vulnerability assessment and critical component identification in adaptive network topologies. The proposed measure is applied to power system vulnerability analysis, with performance demonstrated on the IEEE 30-, 57- and 118-bus test system, outperforming relevant methods from the state-of-the-art. The proposed framework is deterministic (guaranteed), analytically obtained (interpretable) and generalizes well with changing network parameters, providing a complementary tool to power system vulnerability analysis and planning.

Adaptive honeypots are being widely proposed as a more powerful alternative to the traditional honeypot model. Just as with typical honeypots, however, one of the most important concerns of an adaptive honeypot is environment deception in order to make sure an adversary cannot fingerprint the honeypot. The threat of fingerprinting hints at a greater underlying concern, however; this being that honeypots are only effective because an adversary does not know that the environment on which they are operating is a honeypot. What has not been widely discussed in the context of adaptive honeypots is that they actually have an inherently increased level of susceptibility to this threat. Honeypots not only bear increased risks when an adversary knows they are a honeypot rather than a native system, but they are only effective as adaptable entities if one does not know that the honeypot environment they are operating on is adaptive as wekk. Thus, if adaptive honeypots become commonplace - or, instead, if attackers even have an inkling that an adaptive honeypot may exist on any given network, a new attack which could develop is a “blind confusion attack”; a form of connection which simply makes an assumption all environments are adaptive honeypots, and instead of attempting to perform a malicious strike on a given entity, opts to perform non-malicious behavior in specified and/or random patterns to confuse an adaptive network's learning.

Networked control design is essential to enable normal operation and further accomplish performance improvement of the cyber-physical systems. In this work, a resilient control scheme is presented for the networked nonlinear system under the denial-of-service (DoS) attack and the system uncertainty. Through synthesizing a self regulation system, this scheme is capable of releasing the prescribed performance when attack is active and recovering that in finite-time after the attack is slept. Meanwhile, the neural network is employed to approximate the system uncertainty. Particularly, the update law possesses the non-certainty-equivalent (NCE) structure, and then the impact of the DoS attack is totally isolated. Finally, the numerical simulation is presented to illustrate the effectiveness and benefits of the estimation scheme and the control design.

Internet of Things (IoT) is penetrating into every aspect of our personal lives including our body, our home and our living environment which poses numerous security challenges. The number of heterogeneous connected devices is increasing exponentially in IoT, which in turn increases the attack surface of IoT. This forces the need for uniform, distributed security mechanism which can efficiently detect the attack at faster rate in highly scalable IoT environment. The proposed work satisfies this requirement by providing a security framework which combines Fog computing and Software Defined Networking (SDN). The experimental results depicts the effectiveness in protecting the IoT applications at faster rate

This paper develops an adaptive neural network (NN) asymptotic tracking control scheme for nonstrict-feedback switched nonlinear systems with unknown nonlinearities. The NNs are used to dispose the unknown nonlinearities. Different from the published results, the asymptotic convergence character is achieved based on the bound estimation method. By combining some smooth functions with the adaptive backstepping scheme, the asymptotic tracking control strategy is presented. It is proved that the fabricated scheme can guarantee that the system output can asymptotically follow the desired signal, and also that all signals of the entire system are bounded. The validity of the devised scheme is evaluated by a simulation example.

The model-free adaptive security tracking control (MFASTC) problem of nonlinear networked control systems is explored in this paper with DoS attacks and delays consideration. In order to alleviate the impact of DoS attack and RTT delays on NCSs performance, an attack compensation mechanism and a networked predictive-based delay compensation mechanism are designed, respectively. The data-based designed method need not the dynamic and structure of the system, The MFASTC algorithm is proposed to ensure the output tracking error being bounded in the mean-square sense. Finally, an example is given to illustrate the effectiveness of the new algorithm by a comparison.

Batched network coding is a low-complexity network coding solution to feedbackless multi-hop wireless packet network transmission with packet loss. The data to be transmitted is encoded into batches where each of which consists of a few coded packets. Unlike the traditional forwarding strategy, the intermediate network nodes have to perform recoding, which generates recoded packets by network coding operations restricted within the same batch. Adaptive recoding is a technique to adapt the fluctuation of packet loss by optimizing the number of recoded packets per batch to enhance the throughput. The input rank distribution, which is a piece of information regarding the batches arriving at the node, is required to apply adaptive recoding. However, this distribution is not known in advance in practice as the incoming link's channel condition may change from time to time. On the other hand, to fully utilize the potential of adaptive recoding, we need to have a good estimation of this distribution. In other words, we need to guess this distribution from a few samples so that we can apply adaptive recoding as soon as possible. In this paper, we propose a distributionally robust optimization for adaptive recoding with a small-sample inferred prediction of the input rank distribution. We develop an algorithm to efficiently solve this optimization with the support of theoretical guarantees that our optimization's performance would constitute as a confidence lower bound of the optimal throughput with high probability.

Batched network coding (BNC) is a low-complexity solution to network transmission in feedbackless multi-hop packet networks with packet loss. BNC encodes the source data into batches of packets. As a network coding scheme, the intermediate nodes perform recoding on the received packets instead of just forwarding them. Blockwise adaptive recoding (BAR) is a recoding strategy which can enhance the throughput and adapt real-time changes in the incoming channel condition. In wireless applications, in order to combat burst packet loss, interleavers can be applied for BNC in a hop-by-hop manner. In particular, a batch-stream interleaver that permutes packets across blocks can be applied with BAR to further boost the throughput. However, the previously proposed minimal communication protocol for BNC only supports permutation of packets within a block, called intrablock interleaving, and so it is not compatible with the batch-stream interleaver. In this paper, we design an intrablock interleaver for BAR that is backward compatible with the aforementioned minimal protocol, so that the throughput can be enhanced without upgrading all the existing devices.

Adaptive authentication systems identify and enforce suitable methods to verify that someone (user) or something (device) is eligible to access a service or a resource. An authentication method is usually adapted in response to changes in the security risk or the user's behaviour. Previous work on adaptive authentication systems provides limited guidance about i) what and how contextual factors can affect the selection of an authentication method; ii) which requirements are relevant to an adaptive authentication system and iii) how authentication methods can affect the satisfaction of the relevant requirements. In this paper, we provide a holistic framework informed by previous research to characterize the adaptive authentication problem and support the development of an adaptive authentication system. Our framework explicitly considers the contextual factors that can trigger an adaptation, the requirements that are relevant during decision making and their trade-offs, as well as the authentication methods that can change as a result of an adaptation. From the gaps identified in the literature, we elicit a set of challenges that can be addressed in future research on adaptive authentication.

A service-based system (SBS) dynamically composes third-party services to deliver comprehensive functionality. As adaptive systems, SBSs can substitute equivalent services within the composition if service operations or workflow requirements change. Substituted services must maintain the original SBS quality of service (QoS) constraints. In this paper, we add security as a QoS constraint. Using a model problem of a SBS system created for self-adaptive system technology evaluation, we demonstrate the applicability of security assurance cases and service security profile exchange to build in security awareness for more informed SBS adaptation.

This work proposes an event-triggered adaptive asymptotic tracking control scheme for flexible robotic manipulators. Firstly, by employing the command filtered backstepping technology, the ``explosion of complexity'' problem is overcame. Then, the event-triggered strategy is utilized which makes that the control input is updated aperiodically when the event-trigger occurs. The utilized event-triggered mechanism reduces the transmission frequency of computer and saves computer resources. Moreover, it can be proved that all the variables in the closed-loop system are bounded and the tracking error converges asymptotically to zero. Finally, the simulation studies are included to show the effectiveness of the proposed control scheme.

The output feedback problem of finite-time command filtering for nonlinear systems with random disturbance is addressed in this paper. This is the first time that command filtering and output feedback are integrated so that a nonlinear system with random disturbance converge rapidly in finite time. The uncertain functions and unmeasured states are estimated by the fuzzy logic system (FLS) and nonlinear state observer, respectively. Based on the adaptive framework, command filtering technology is applied to mitigate the problem of ``term explosion'' inherent in traditional methods, and error compensation mechanism is considered to improve the control performance of the system. The developed output feedback controller ensures the boundedness of all signals in the stochastic system within a finite time, and the convergence residual can converge to a small region. The validity of this scheme is well verified in a numerical example.

This paper is concerned with the problem of adaptive finite-time prescribed performance control for a category of uncertain nonlinear systems subject to fuzzy dead-zone input. Via combining the technologies of command filter and backstepping control, the ``singularity'' and the ``explosion of complexity'' issues within controller design procedure are avoided. Moreover, by designing a state observer and utilizing the center-of-gravity theorem, the unmeasured states of system are estimated and the fuzzy issue result from fuzzy dead-zone input is disposed, respectively. Meanwhile, a finite-time fuzzy controller is constructed via combining with finite-time stability criterion, which guarantees all the signals in closed-loop system are convergent and the trajectory of tracking error also strictly evolves within a predefined range in finite time. At last, some simulation results confirm the viability of presented theoretical results.

Adaptive feedback cancellation (AFC) method is widely adopted for the purpose of reducing the adverse effects of acoustic feedback on the sound reinforcement systems. However, since the existence of forward path results in the correlation between the source signal and the feedback signal, the source signal is mistakenly considered as the feedback signal to be eliminated by adaptive filter when it is colored, which leads to a inaccurate prediction of the acoustic feedback signal. In order to solve this problem, prediction error method is introduced in this paper to remove the correlation between the source signal and the feedback signal. Aiming at the dilemma of Modified Least Mean Square (MLMS) algorithm in choosing between prediction speed and prediction accuracy, an improved MLMS algorithm with a variable step-size scheme is proposed. Simulation examples are applied to show that the proposed algorithm can obtain more accurate prediction of acoustic feedback signal in a shorter time than the MLMS algorithm.

Critical infrastructures have to withstand advanced and persistent threats, which can be addressed using Byzantine fault tolerant state-machine replication (BFT-SMR). In practice, unattended cyberdefense systems rely on threat level detectors that synchronously inform them of changing threat levels. However, to have a BFT-SMR protocol operate unattended, the state-of-the-art is still to configure them to withstand the highest possible number of faulty replicas \$f\$ they might encounter, which limits their performance, or to make the strong assumption that a trusted external reconfiguration service is available, which introduces a single point of failure. In this work, we present ThreatAdaptive the first BFT-SMR protocol that is automatically strengthened or optimized by its replicas in reaction to threat level changes. We first determine under which conditions replicas can safely reconfigure a BFT-SMR system, i.e., adapt the number of replicas \$n\$ and the fault threshold \$f\$ so as to outpace an adversary. Since replicas typically communicate with each other using an asynchronous network they cannot rely on consensus to decide how the system should be reconfigured. ThreatAdaptive avoids this pitfall by proactively preparing the reconfiguration that may be triggered by an increasing threat when it optimizes its performance. Our evaluation shows that ThreatAdaptive can meet the latency and throughput of BFT baselines configured statically for a particular level of threat, and adapt 30% faster than previous methods, which make stronger assumptions to provide safety.

E-learning enables the transfer of skills, knowledge, and education to a large number of recipients. The E-Learning platform has the tendency to provide face-to-face learning through a learning management system (LMS) and facilitated an improvement in traditional educational methods. The LMS saves organization time, money and easy administration. LMS also saves user time to move across the learning place by providing a web-based environment. However, a few students could be willing to exploit such a system's weakness in a bid to cheat if the conventional authentication methods are employed. In this scenario user authentication and surveillance of end user is more challenging. A system with the simultaneous authentication is put forth through multifactor adaptive authentication methods. The proposed system provides an efficient, low cost and human intervention adaptive for e-learning environment authentication and monitoring system.